It has heretofore been difficult for a machinist to hold an irregularly-shaped part on a work table for drilling a hole, planing or finishing its surfaces, or performing other machining and work operations on the part. Typically, an irregularly-shaped part is held against the work table by a hydraulically-operated or pneumatically-operated clamp device which may have sophisticated and costly pumps, control valves, pressurized fluid lines, and pressure plates. These known clamping and holding devices are unacceptable for securing irregularly-shaped parts on a work table because they are expensive, and because of their complexity, they require excessive set-up time and effort by the machinist.
It is also known that hydraulically-actuated clamping or holding mechanisms can be unacceptable because the hydraulic fluid leaks onto the work surface thereby creating a nuisance. A problem sometimes encountered using a hydraulically-actuated clamping mechanism is that the hydraulic fluid leaks around the joints and couplings of the pressurized fluid lines. In certain machining operations, it is not suitable for hydraulic fluid to be on the work surface because it attracts and retains metal shavings and other undesirable materials that only hinder subsequent machining operations.
Pneumatically-operated or spring-biased clamps are other known devices for holding down irregularly-shaped parts; and while they do not cause a nuisance such as that found in the use of hydraulically-actuated clamps, they are not without their own problems. Pneumatically-actuated clamps use high pressure air lines that necessitate use of a compressor and other complicated and expensive apparatus for actuating the pressure members of the clamp. Spring biased clamps use springs, cams, and other mechanical parts that are susceptible to breakage or mechanical failure.
Another problem with prior clamping devices is that they require complex and expensive elements such as control valves to actuate and return the pressure-applying members that abut the irregularly-shaped part. Normally, a control valve is required in the pneumatic or hydraulic pressure lines to cause the pressure-applying members to be extended as well as retracted. An equivalent device is also required for the mechanical, spring-biased type clamps. The cost of having these in-line controls is undesirable, and there is always the problem of malfunctioning and mechanical failure.
Hence, the invention herein is concerned with, but not limited to, an improved motion and pressure transferring device for holding irregularly-shaped parts on a work table for machining and working operations.